r - Changing the Appearance of Facet Labels size -

i know question asked here: is there way increase height of strip.text bar in facet?

i want decrease height of strip.text bar without changing text size. in current case there space left between text , strip bar walls.

here tried far,

library(gcookbook) # data set library(ggplot2)  ggplot(cabbage_exp, aes(x=cultivar, y=weight)) + geom_bar(stat="identity") + facet_grid(.~ date) + theme(strip.text = element_text(face="bold", size=9,lineheight=5.0), strip.background = element_rect(fill="lightblue", colour="black", size=1)) 

in case seems lineheight not affect if changed 5. why?
how can make strip bar size little smaller keeping text size same?

edit after @sandy muspratt answer

we able reduce strip size if there 1 row of facets.

g = ggplotgrob(p) g$heights[c(3)] = unit(.4, "cm")  # set height  grid.newpage() grid.draw(g) 

however, in real data have many rows of plot below , when changed elements of g$heights nothing happened!

p = ggplot(cabbage_exp, aes(x=cultivar, y=weight)) + geom_bar(stat="identity") +   facet_wrap(~ date,ncol = 1) +   theme(strip.text = element_text(face="bold", size=9),         strip.background = element_rect(fill="lightblue", colour="black",size=1)) 

 g = ggplotgrob(p) g$heights #    [1] 5.5pt               0cm                 0.66882800608828cm  #1null               0cm                 0.193302891933029cm #     [7] 0.66882800608828cm  1null               0cm                 #0.193302891933029cm 0.66882800608828cm  1null               #    [13] 0.456194824961948cm 0cm                 1grobheight         5.5pt 

then attempted change 1,7 , 11 elements

g$heights[c(3,7,11)] = unit(.4, "cm")  # set height  grid.newpage() grid.draw(g) 

no change in facet label size.

> g$heights  [1] 5.5pt                                                       1grobheight                                                  [3] sum(0.2cm, sum(0.15cm, 0.8128cm, 0cm, 0.15cm), 0.2cm)+0.2cm 0.2                                                          [5] 1null                                                       0cm                                                          [7] 0.193302891933029cm                                         0.2                                                          [9] 1null                                                       0cm                                                         [11] 0.193302891933029cm                                         0.2                                                         [13] 1null                                                       0cm                                                         [15] 0.193302891933029cm                                         0.2                                                         [17] 1null                                                       0.456194824961948cm                                         [19] 0cm                                                         1grobheight                                                 [21] 5.5pt   

use margins

from ggplot2 ver 2.1.0: in theme, specify margins in strip_text element (see here).

library(ggplot2) library(gcookbook) # data set  p = ggplot(cabbage_exp, aes(x=cultivar, y=weight)) + geom_bar(stat="identity") + facet_grid(. ~ date) + theme(strip.text = element_text(face="bold", size=9), strip.background = element_rect(fill="lightblue", colour="black",size=1))    p +   theme(strip.text.x = element_text(margin = margin(.1, 0, .1, 0, "cm"))) 

the original answer updated ggplot2 v2.2.0

your facet_grid chart

this reduce height of strip (all way 0 height if want). height needs set 1 strip , 3 grobs. work specific facet_grid example.

library(ggplot2) library(grid) library(gtable) library(gcookbook) # data set  p = ggplot(cabbage_exp, aes(x=cultivar, y=weight)) + geom_bar(stat="identity") + facet_grid(. ~ date) + theme(strip.text = element_text(face="bold", size=9), strip.background = element_rect(fill="lightblue", colour="black",size=1))  g = ggplotgrob(p)  g$heights[6] = unit(0.4, "cm")  # set height  for(i in 13:15) g$grobs[[i]]$heights = unit(1, "npc") # set height of grobs  grid.newpage() grid.draw(g) 

your facet_wrap chart

there 3 strips down page. therefore, there 3 strip heights changed, , 3 grob heights changed.

the following work specific facet_wrap example.

p = ggplot(cabbage_exp, aes(x=cultivar, y=weight)) + geom_bar(stat="identity") +   facet_wrap(~ date,ncol = 1) +   theme(strip.text = element_text(face="bold", size=9),         strip.background = element_rect(fill="lightblue", colour="black",size=1))  g = ggplotgrob(p)  for(i in c(6,11,16)) g$heights[[i]] = unit(0.4,"cm")   # 3 strip heights changed for(i in c(17,18,19)) g$grobs[[i]]$heights <-  unit(1, "npc")   # height of 3 grobs changed  grid.newpage() grid.draw(g) 

how find relevant heights , grobs?

g$heights returns vector of heights. 1null heights plot panels. strip heights 1 before - 6, 11, 16.

g$layout returns data frame names of grobs in last column. grobs need heights changed names beginning "strip". in rows 17, 18, 19.

to generalise little

p = ggplot(cabbage_exp, aes(x=cultivar, y=weight)) + geom_bar(stat="identity") +   facet_wrap(~ date,ncol = 1) +   theme(strip.text = element_text(face="bold", size=9),         strip.background = element_rect(fill="lightblue", colour="black",size=1))  g = ggplotgrob(p)  # heights need changing in positions 1 less plot panels pos =  c(subset(g$layout, grepl("panel", g$layout$name), select = t)) for(i in pos) g$heights[i-1] = unit(0.4,"cm")  # grobs need heights changed: grobs = which(grepl("strip", g$layout$name)) for(i in grobs) g$grobs[[i]]$heights <-  unit(1, "npc")       grid.newpage() grid.draw(g) 

multiple panels per row

nearly same code can used, title , legend positioned on top. there change in calculation of pos, without change, code runs.

library(ggplot2) library(grid)  # data df = data.frame(x= rnorm(100), y = rnorm(100), z = sample(1:12, 100, t), col = sample(c("a","b"), 100, t))  # plot p = ggplot(df, aes(x = x, y = y, colour = col)) +    geom_point() +    labs(title = "made-up data") +     facet_wrap(~ z, nrow = 4) +    theme(legend.position = "top")  g = ggplotgrob(p)  # heights need changing in positions 1 less plot panels pos =  c(unique(subset(g$layout, grepl("panel", g$layout$name), select = t))) for(i in pos) g$heights[i-1] = unit(0.2, "cm")  # grobs need heights changed: grobs = which(grepl("strip", g$layout$name)) for(i in grobs) g$grobs[[i]]$heights <-  unit(1, "npc")   grid.newpage() grid.draw(g)